Cytoplasmic localization in eggs is a fundamental mechanism of development. In this process molecules and organelles become distributed asymmetrically in the cytoplasm of the egg, so that they are inherited by different cells of the embryo, and create the initial differences between them. Despite its fundamental importance to embyrogenesis in most species, very little is known about its molecular mechanism. Several examples of localization in the Xenopus egg are known to require intact microtubules. In this study, we propose to investigate the roles of microtubule motor proteins of the kinesin family in these localizations in Xenopus. We have previously shown that one of the kinesins, XklP1, is required for the correct localization of germ plasm, a cytoplasmic component necessary for germ cell formation. We will further investigate the molecular basis of germ plasm localization, analyze the roles of already characterized kinesin family members in this and two other examples of localization and identify new members of this multigene family expressed in Xenopus oocytes. This work is of importance for the molecular understanding of a basic mechanism of development, and for the understanding of the multiple roles of motor proteins in a single cell.